In many research and medical applications specimens are mounted on slides. It is known in the scientific and medical fields that slides are small rectangular plates—made of glass or other rigid and transparent materials—that are used for receiving and holding a target sample for use with a scientific or medical instrument such as a microscope. Often, the control of the temperature of the slide is of critical importance to the observation process. For that reason many instruments that handle the slide often rely on a temperature controlled surfaces. An example of such an instrument is an automated immunohistochemistry (IHC) slide stainer with a heated slide pad. For those instruments, independent temperature validation is commonly required to ensure proper functioning of the slide mount heat pad. In fact, for many US labs a failure to maintain accurate logs of independent temperature validation can result in fines, penalties, or loss of certification.
However, the slide and the mounted specimen typically experience other critical temperature exposures prior to interacting with those instruments. At any of these other exposures, there is the chance of negative consequences. For example, an elevated temperature exposure can alter, compromise, or even destroy the specimen mounted on a slide. Sometimes, the changes and/or damage may be falsely attributed to the specimen resulting in false data being observed and used for the work to which the specimen was provided. In a medical lab, the temperature error may lead to misdiagnosis or a failure to diagnose a tissue sample.
Yet, presently pathologists have no way of knowing with any certainty the range of temperatures the patient's tissue has been exposed to. Similarly, pathologists are unaware of the duration of time the tissue has been exposed to those temperatures.
To illustrate the potential for damaging temperature exposures take as example a typical chain of custody followed in clinical pathology laboratories: 1) a bulk tissue specimen is received by a lab tech known as a histotech, 2) the specimen is accessioned, 3) the specimen is grossed, 4) the specimen is processed, 5) the specimen is embedded in paraffin, 6) the specimen is frozen, 7) the specimen is cut into sections approximately three to four microns thick or as requirements dictate, 8) the specimen is placed into a heated water bath, 9) the specimen sections are mounted onto microscope glass slides, 10) the specimen is dried in an oven, 11) the routine or advanced staining procedures are applied to the specimen, and finally 12) the specimen is transferred to a pathologist for observation and analysis.
During every stage of this process the temperature and duration of exposure are critical because the morphology or biochemistry of the tissue can be greatly altered by a failure to observe the proper protocol required of that process. Some stages are particularly ripe for errors or temperature related damages to the specimen. Note for example that a typical water bath is heated to a point in the range of approximately 45-55° F. If the water bath is too hot, the tissue will explode across the water bath. Similarly, even within a normal range of temperature if the tissue is left on the water bath for too long then the tissue will expand thus dramatically altering the morphology. Morphology changes are extremely impactful on any procedure or observation made downstream in the custody chain.
Another step with a high potential for thermal damage occurs in the drying process. After the histotech completes the microtomy process (slicing the bulk specimen into a mountable slice, warming it in the water bath, and mounting the slice to a slide) the slides are placed into a conventional drying oven. This oven helps remove excess water from underneath the tissue sections while improving the adhesion between the patient's tissue and the glass slide thus reducing the potential for the specimen tissue washing off the slide during the staining process (which can be extensive—the IHC process can range from approximately one and a half hour to eight hours). This step also pre-melts the paraffin within and around the tissue specimen. The oven temperature is typically set between 60-65° C. However, it is common for histotechs to place the slide into the drying oven beyond the recommended time due to a range of issues such as other work demands, distractions, negligence, forgetfulness, extended bathroom breaks, etc. This drying oven temperature and the amount of exposure time is critical because it can mimic HIER (Heat Induced Epitope Retrieval) especially if set too high. Also, if the slide sits in this oven too long then the specimen tissue will begin to bubble (similar to boiling) which causes the tissue to lift off of the glass thus changing the morphology.
The pathologist may have requested one or multiple routine staining procedures (e.g. Hematoxylin & Eosin Staining, also known as H&E staining). The Pathologist may have also or alternatively requested one or multiple advanced stains (e.g. IHC). The desired staining may require manual staining or the use of an automated IHC slide stainer, following the completion of the oven drying step. Each temperature setting or program is preselected through a custom written protocol that is specific to each stain. Regardless of the type of preparation, procedure, or test each slide will come in direct contact with a variety of temperatures.
A pathologist questioning the preparation of a specimen will find the temperature history extremely useful to understanding the specimen's characteristics. Unfortunately, no slide exists that can track the temperature over time and communicate a log of that information in real time or store it for later access. The following invention relates to a new slide product that addresses this concern and others (such as ease of tracking, identification, and accountability).